Art of drawing ferrous metal



Patented Oct. 15, 1940 ART OF DRAWING FERROUS METAL Albert J. Saukaitis, Philadelphia, Pa., assignor to American Chemical Paint Company, Ambler, Pa.,-a corporation of Delaware No Drawing.

Application March 23, 1938,

Serial N0. 197,629

13 Claims; (Cl. 205-8) This invention relates to the art of metal working in which metallic objects are rolled, drawn, squeezed, or otherwise subjected to pressure in order to change their size, their shape, or both, and is particularly directed to the art of drawing wire, rod, or seamless tubing, of ferrous metal.

More particularly, the invention concerns the formation of an adherent, lubricating coating on objects which are to bedrawn through dies or over mandrels or which are to be otherwise deformed in such a Way that there is friction between the metallic surface and the deforming agency.

The principal object of the invention is to prepare ferrous metal objects (i. e., objects which have at least a ferrous metal surface) for a drawing or analogous deforming operation by forming thereon an adherent lubricating coating of copper. In attaining this object I have provided a method for producing coatingsof copper which are extremely smooth, tenaciously adherent and durable. Another object is to provide a solution which will deposit copper coatings of the desired character and a further object is to provide substantially dry admixtures which may be dissolved in water or in acid solutions for preparing or replenishing the solutions employed with my improved method. I also contemplate the production, as new articles of manufacture, of ferrous metal billets or -like objects bearing an adherent lubricating coating of copper as will further appear.

Still other objects of my invention are to provide a method of the character described which is relatively insensitive to the presence of grease on the object to be drawn or deformed; to provide a method in which the coating may be allowed to grow to a substantialthickness without loss of adhesion; to provide a coating of the character described which will result in much reduced wear of the drawing die or similar tools as well as a smoother surface on the finished article and a lower average power consumption during the drawing or deforming operation; to provide a lubricating coating of the character described which will withstand a number of draughts through the die without flaking or peeling off; and to provide a method which will produce satisfactory coatings over a wide range of temperatures and bath compositions.

In attaining the foregoing objects I have discovered that dilute acid solutions of copper salts such as copper sulfate, to which have been added certain organic corrosion inhibitors, have the ability, in the presence of the ions of the halogenous acids, to produce with great rapidity on iron or steel surfaces, an-extremely adherent, bright, durable and uniform lubricating coating of copper. By halogenous acids I mean hydrofluoric, hydrochloric, and hydrobromic acid. The ions of 5 hydriodic acid are not compatible with my solutions for reasons which will appear-hereinbelow. In carrying out the process of my invention the metal to be coated is immersed for a period of seconds to 15 minutes, more or less in a 10 solution whose temperature may range from ordinary room temperature to the boiling point of the solution. The speed of the coating action increases as the temperature is raised. The solution employed must contain dissolved copper, free 5 acid, halogen ions, and a small quantity of one or more of certain organic inhibitors of the corrosion of ferrousmetals by acids.

Among the inhibitors which have proven satisfactory are basic substances extracted from ani- 20 mal distillates, basic substances extracted from coal tar, aldehyde amine reaction products, aldehyde-ketone reaction products, amino acids, alkaloids such as quinine and quinoidine, sulfonated and sulfurized derivatives of thesebases, and 25 many others. Specific examples of compounds which are effective in my process are dimethyl naphthoquinaldine, anhydroformaldehyde aniline, tetramethyl-diaminodiphenylmethane, acetaldehyde orthotoluidine condensation products, 30 salts of such condensation products, etc. Resinous, nitrogen containing substances are very effective when they are sufficiently soluble in theacid coating solution.

Because of the large number of substances I have tested, I believe myself justifled in assuming that all the organic, nitrogenous, inhibitors of appreciable, solubility in my improved solutions, are effective in my improved process.

Inhibitors of acid-corrosion vary greatly in strength. For the purposes of this disclosure, I shall include among the inhibitors only those substances which have strong inhibiting properties in dilute solutions of halogenous acids, such as hydrochloric acid, without the assistance of the promoting'effect of copper described in my U. S. Patent No. 2,049,517. Very weak inhibitors, or substances which have appreciable inhibiting strength only in the presence of dissolved copper, such as ortho-toluidine, aniline, etc., are not to 5 be considered inhibitors ior the purposes of this specification, as such materials are not operative to secure my improved results.

Certain organic, nitrogenous, inhibitors such. as the thioureas are ineifective, apparently because of their reaction with the copper'in my coating solution .to form insoluble or otherwise ineffective materials. The same is true of the cuprous chloride, cupric sulfate, cupric nitrate,

cupric acetate, cupric benzoate, etc. The halogen .ions may be introduced into the solution in the form of any convenient compound such as sodium chloride, ammonium bromide, zinc bromide, ferric chloride, hydrochloric acid, etc.

The presence in the solution of non-essential ions has little eifect on the operation of the process within the limits of compatibility familiar to every chemist. The presence in the solution of large quantities of sodium or ferrous iron, for instance, seems to be quite without effect unless the content in salts of these metals is sufficient to salt out the inhibitor used. Anions such as sulfate, phosphate, etc., are likewise harmless. Cations of metals much less basic than iron such/ as arsenic, mercury, etc., are to be avoided if the color of the coating produced is to remain that of fine copper. Cther metals such as zinc, calcium, etc., are not harmful.

As an example of the use of my improved process and solution, Lshall now describe its application to the coating of wire which is to be drawn to finer size. i

A solution is prepared ma vat-of wood, rubberlined steel, or other unattacked material and which is equipped with steam coils or other suitable heating means- This solution may be composed as follows:

Formula N0. 1

Copper sulfate pentahydrate lb 0.250 Common salt lb 0.083 Sulphuric acid, 66 B gal 0.030 Inhibitor A ounce 0.05 Water to make"; gal 1.000

Inhibitor A consists of a concentrated solution of the reaction product of ortho-toluidine and formaldehyde in hydrochloricacid, containing about 40% of active inhibitor by weight.

The solution is heated to about 150 F. more or less depending upon the speed of the coating action desired. The coils of wire which have been freed of scale by pickling are thenimmersed in the solution for from 30 seconds to 5 minutes depending on the type of steel being coated, the thickness of coating desired, etc. Ordinarily, a coating of suflicient thickness is produced in about one minute.

It will be understood that the ingredients and their proportions as given above are only illus trative and wide variations in composition are possible as will be understood by anyone familiar with the art, without departing from the spirit of the invention.

For most types of steel, I prefer to maintain the copper content of the solution at from A to 2 02s. per gallon. The higher copper concentration gives a somewhat more rapid coating action, too, but, too high a copper content causes some dulling of the coating. The concentration of hibitor.

. iodide with the liberation of free iodine;

halide ion whichlprefer is between 0.04 and- 2.0

normal. The solution is insensitive to wide variations in content of halide ion.v In general, 'it may be said thata halide ion content which is too low leads to non-adherent coatings; one

which is too high results in a considerable slowv ing down of the coating operation- The acidity-of the solution may range from 0.1 N.'to 5 N. No great change is produced by varying the acidity of the solution. In general, it may be said that insufficient acidity causes nonadherent slow coating; excessive acidity causes the coating to be dull in appearance, and slow to form. Q w

The concentration of inhibitor preferred is somewhat difficult to specify. The quantity which is, best varies with the strength of the in- Of the powerful aldehyde-amine condensation products, 0.01 to 0.10 oz. per gallon is suificient; of weaker inhibitors, like the lower quinoline bases, ten times as much may be used. In any case, enough inhibitor is used to produce tight, smooth, coatings without slowing down the action of the solution excessively. The correct amount of any specific inhibitor is easily found by trial.

Other solutions which may be used to produce good coatings of copper are given below:

Water to make 1.000

Note-The coal tar yridine mentioned'above is an acid extracted fraction 0 coal tar boiling above 200 C.

Formula N0. 3

Copper sulfate pentahydrate lb Phosphoric acid, 75% gal.. 0.083 1 Sodium chloride lb 0.100 Anhydroformaldehyde aniline oz 0.05 Water to make gal 1.000

Formula No. 4

Copper sulfate 'pentahydrate.... lb 0.250 Sulphuric acid, 66 B gal 0.030 s ium fluoride lh 0.200 Anhydroformaldehyde aniline, oz 0.05 Water to make l 1.000

The above examples will illustrate the variety of compositions which are operative in my'improved process. It is to be noted that the iodides may not be used in my process or composition because of the well-known action of cupric ion on iodide ion to precipitate the insoiuble cuprous The use of bromides or fluorides in solutions containing phosphoric acid is. likewise attended with difficulties since these tend to form complexes which cause the precipitation of the inhibitor. With these exceptions, one may select acid, halogen, etc., almost at will, with due regard, as previously pointed out, to the chemical compatibilities of the solutions.

I have discovered that new and useful compositions maybe prepared for use in making up and replenishing copper-coating solutions according to my invention. -As stated above, the solutions used in carrying out my process must contain, in addition to'water, copper ions, halide ions, hydrogen ions, and an inhibitor. These ions, as well as the inhibitor, may be supplied to the solution combined with any inert or harmless ions-or substances within the limits of compatibility which Formula No.

Pounds Copper sulfate monohydrate 0.69 Common sal 0.28 Inhibitor A 0.03

Inhibitor A is the same concentrated solution mentioned under Formula No. 1. The dry ingredients readily take up the small quantity of water present in the liquid inhibitor when the material is mixed.

Three to six ounces of the material of this formula are simply dissolved in each gallon of a 3% solution of concentrated sulphuric acid by volume to form the copper-coating solution. Further additions of the material and of sulphuric acid may be made as required to replenish the used solution.

If the ,hydrogen ion content of the solution is wholly or partly supplied by muriatic acid, the following dry admixture. is very convenient for furnishing the necessary copper ion and inhibitor:

Formula No. 6

. Pounds Copper carbonate 0.95

, Anhydroformaldehyde aniline 0.05

Two to four. ounces of this materialis dissolved per gallon of a 10% solution of 20 B. muriatic acid by volume. Replenishment of this depleted solution may be accomplished with more of the above material;

Many variations of the invention will occur 'to' one skilled in the art. Depending on the circumstances, it may be convenient to make dry admixtures containing all of .the ingredients necessary to supply the necessary constituents of the coating solution, or any one or more of these ingredients may be omitted from the admixture and supplied separately to the solution, as illus-' trated above. v

- To make up a solution in accordance with my invention when liquid concentrated acids are not easily available to the user, I may make the fol- From one pound to one and one quarter pounds of this material, dissolved in water to make one gallon, sufiice to give a good coating bath.

' It will be noted that this admixture-contains sodium acid sulfate. For the same purpose in this or' other admixtures made according to my invention, I may employ any other suitable acid salt or solid acid.

' I claim:

1. The method of applying a metal lubricant to the surface of ferrous metal objects in prepa- 5 ration for a drawing or analogous deforming operation, which method comprises treating the surface with a solution comprising copper ions, hydrogen ions, ions of an acid from the class consisting of hydrochloric, hydrobromic'and hy- 10 drofiuoric acids, and a nitrogenous, organic, basic inhibitor of the type used to restrain the action of acids upon ferrous metals, said inhibitor being of appreciable solubility and stable in the solution, the concentration of the copper ion being between 0.25 and 2 ounces per gallon.

2. The method of claim 1 wherein the concentration of halide ion is between 0.04 and 2.0 normal, and the concentration of hydrogen ion corresponds to a free acid content of from 0.1 normal to 5.0 normal.

' 3. A solution for use in applying a copper coating to a ferrous metal surface, said solution comprising copper ions in a concentration between 0.25 and 2 ounces per gallon, hydrogen ions, ions of an acid from the class consisting of hydrochloric, hydrobromic and hydrofluoric, and a nitrogenous, organic, basic inhibitor of the type used to restrain the action of acids upon ferrous metals, said inhibitor being of appreciable solubility and stable in the solution 4. The solution of claim 3 wherein the concentration of the ions of acid from the specified class lies between 0.04 and 2.0 normal and the concentration of hydrogen ion correspondsto a free acid content of from 0.1 to 5.0 normal.

5. A substantially dry admixture for use in preparing and replenishing acid copper coating solutions of the character herein disclosed, said admixture comprising an acid soluble copper compound, a nitrogenous organic basic inhibitor; of the type used to restrain the action of acids upon ferrous metals, and a water soluble halide salt from the class consisting of chlorid bromides and fluorides, said inhibitor being of appreciable solubility and stable in a solution of said acid soluble copper compound.

6. The admixture of claim 5 which also comprises a solid, water soluble acidic compound.

7. The method of applying a metal lubricant to the surface of ferrous metal objects in prepsration for a. drawing or analogous deforming operation, which method comprises; treating it with an admixture comprising copper sulfate pentahydrate, common salt, sulphuric acid, water and an inhibitor comprising the reaction product of ortho-toluidine and formaldehyde the quantity of copper sulfate pentahydrate being suflicient to yield a concentration of copper ions of between 0.25 and 2 ounces per gallon.

8. The method of applying a metal lubricant to the surface of ferrous metal objects in preparation for a. drawing or analogous deforming operation, which method comprises treating it with an admixture comprising cupric chloride dihy- 5 drate, hydrochloric acid, water and coal tar Pyridine boiling above 200 0., the quantity of cupric chloride dihydrate being sufllcient to yield a concentration of copper ions of between 0.25 and 2 ounces per gallon.

9. The method of applying a metal lubricant to the surface of ferrous metal objects in prepaan admixture comprising copper sulfate pentaaction of acids upon ferrous metals, said inhibi-' tor being of appreciable solubility and stable in the solution, the concentration of the copper ion being between 0.25 and 2 ounces per gallon.

11. The method of claim 10 wherein the concentration of halide ion is between 0.04 and 2.0 normal, and the concentration of hydrogen ion corresponds to a free acid content of from 0.1 normal to 5.0 normal.

12. The method of applying a metal lubricant to the surface of metal objects in preparation for a drawing or analogous deforming operation, which method comprises treating it with a solution comprising copper sulfate, common salt, sulphuric acid, water and a nitrogenous, organic, basic inhibitor of the type used to restrain the action of acids upon ferrous metals, said inhibitor being of appreciable solubility and stable in the solution, the quantity of copper sulfate being sufficient to yield aconcentration of copper ions of between 0.25 and 2 ounces per gallon.

13. A solution for use in applying a copper coating to a ferrous metal surface, said solution comprising copper sulfate, common salt, sulphuric acid, water and a nitrogenous, organic, basic inhibitor of the type used to restrain the action of acids upon ferrous metals, said inhibitor being of appreciable solubility and stable in the solution, the quantity of copper sulfate being sufiicient to yield a concentration of copper ions of between 0.25 and 2 ounces per gallon.

ALBERT J. SAUKAITIS. 

